Study of ash deposition during coal combustion under oxyfuel conditions

Patrocinador:
The work presented was financially supported by the RFCS projects
BOFCOM and ECOSCRUB, the Dutch National project CATO2,
and the Dutch National program EOS-LT, Consortium Biomass
Co-firing. The fine work of Peter Heere in operating the reactor is
highly acknowledged

Resumen:

This paper presents a comparative study on ash deposition of two selected coals, Russian coal and lignite,
under oxyfuel (O₂/CO₂) and air combustion conditions. The comparison is based on experimental results
and subsequent evaluation of the data and observeThis paper presents a comparative study on ash deposition of two selected coals, Russian coal and lignite,
under oxyfuel (O₂/CO₂) and air combustion conditions. The comparison is based on experimental results
and subsequent evaluation of the data and observed trends. Deposited as well as remaining filter ash (fine
ash) samples were subjected to XRD and ICP analyses in order to study the chemical composition and
mineral transformations undergone in the ash under the combustion conditions. The experimental
results show higher deposition propensities under oxyfuel conditions; the possible reasons for this are
investigated by analyzing the parameters affecting the ash deposition phenomena. Particle size seems
to be larger for the Russian coal oxy-fired ash, leading to increased impaction on the deposition surfaces.
The chemical and mineralogical compositions do not seem to differ significantly between air and oxyfuel
conditions.
The differences in the physical properties of the flue gas between air combustion and oxyfuel combustion,
e.g. density, viscosity, molar heat capacity, lead to changes in the flow field (velocities, particle trajectory
and temperature) that together with the ash particle size shift seem to play a role in the observed
ash deposition phenomena[+][-]